Sorry to say, I don't have an explanation for this. The Cancel button should abort the entire series of currently running tasks associated with the GetLatest operation running at the time. Even if it has to wait for a particular transaction to complete, SQL Server's UMS should terminate the transaction rather than laeving it hang, so I do not know if the fault was in Source Control or that the SQL Server's scheduler was not handling the deadlock properly.

If the problem happens consistently, please let us know and we can try to debug it.

Easier said than done -- if I drop the table, how can I then insert into the same table? And if I manually delete the table from source control and commit, SQL Source Control shows me I have a new table to commit to source control rather than a drop table in Get Latest. So reproducing this problem is not so easy for me.